The manufacture of polyurethane profiles in pregiven usable lengths as they are needed for the articles, for example windows, which are to be manufactured individually, is known.
The manufacture of profiles with pregiven usable lengths and which contain a perforated steel pipe so that the polyurethane mass which surrounds the steel pipe fills out also the inside of the pipe is known. The steel pipe lies back on the two front sides of the profile. The profiles are connected at the ends, which ends have a beveled construction, by means of metal corner angles which are pressed with a large force into preformed recesses within the plastic.
In addition, the manufacture of profiles with pregiven usable lengths is known, the core of which consists of wood or an aluminum profile and the outside of which consists also of a polyurethane mass. Both reinforcing profiles spring back at the ends. The corner connection is done by threading a screw into a nut which is cast into the counter profile or by the corner angle connections.
In addition, it is known to produce a window in one piece. For this a separate form is needed for each window size and frame type and still not all areas of dimension can be included. The manufacture is very expensive, the system has little capability for adjustment.
The manufacture of individual usable lengths of profiles in contrast to long profiles, which can be separated as needed and can then be connected, is proven to be of a great disadvantage. Because of the many window sizes the manufacture of individual usable lengths means a great number of different profile lengths, which results in a large expense in the preparation for manufacture, to carry same out and to deliver the product. Up to now it was not possible to manufacture profiles of the abovementioned type in large lengths.
The basic purpose of the present invention is to develop a profile and a mold for forming the profile by coating a preform with plastic. Thus the purpose consists in the development of long plastic profiles, in particular window profiles, made preferably of polyurethane and having an integrated reinforcing preform which permit through severing at any desired location a variable window design with a high quality corner connection.
The invention includes the provision of a mold in which the reinforcing preforms are precisely aligned on the form wall with lengths of approximately 5,000-6,000 mm.
Problems can arise in the manufacture of profiles in forms or molds without taking any special measures especially in situations where the profiles have a greater length than approximately the provided usable length, because in the case of longer profiles the reinforcing preform does not extend exactly straight between its support points at the form ends but is, instead, bent more or less in a vertical and/or a horizontal plane. In particular, the weight of the reinforcing preform causes a downward sag. In the case of the existing manufacture of common usable lengths, deviations from the straight form were not annoying in each case because these deviations were not excessively great due to the relatively small distance between the end supports and due to a precise positioning in the end areas. As a result, the connection of the profiles to, for example, window frames by means of corner angles did not bring with it any special difficulties.
If, however, longer profile rods are manufactured, which by a cutting of suitable pieces to a usable length, it is necessary that the reinforcing preforms have over their entire length exactly the same position relative to the outer shape of the profile. Only then will the correct alignment of the reinforcing preform with respect to the outer shape exist. This alignment is a condition for a good corner connection by means of corner angles. Also one would risk, by a fixing of a very long reinforcing preform only at its ends such great deviations from the correct position, that the spacing of the reinforcing preform walls from the outer wall of the profile becomes too small and it may even happen that the reinforcing preform becomes visible. However, in the situation of small shiftings of the reinforcing preform considerable disadvantages will occur, like streak formations and color differences on the plastic surface and an influence on the heat insulation characteristic.
The inventive form of the abovementioned type is characterized by arranging pins which are rigidly connected to the form box or mold between the ends of the form box at at least one point (fixing point), preferably at several fixing points and engage the reinforcing preform and hold same over its entire length at an even distance from the inside walls of the form box.
Such a form permits also to fix exactly very long reinforcing preforms relative to the inside wall of the form, so that it is assured that at each later cutting or severing location, the reinforcing preform lies exactly correctly relative to the outer wall of the form. Thus it is possible to manufacture the profiles in lengths of approximately 5,000 to 6,000 mm. Experience has shown, that an arrangement of fixing points at intervals of approximately 800 mm. is sufficient.
If the pins are moved not before the plastic is hardened, holes will remain in the profile and are formed from the pins. It is therefore of an advantage to permit the pins to project from such walls of the form box and form surfaces on the profile, which surfaces will not be visible after installation.
Various pin arrangements are possible. Particularly important are pins provided for the purpose of supporting the reinforcing preform against a downward sag. The preform can, however, also experience a considerable hydrostatic lift or pressure through an expanding foam mass which would effect an upward bending. Action can be taken against this with an arrangement wherein an upper set of pins engage and maintain the upper surface of the preform fixed relative to the lower part of the form box. A pin arrangement wherein the upper pin is equidistantly spaced from a pair of laterally spaced lower pins brings about in the simplest manner a securing of the preform against lateral tilting or warping.
Particular advantages are obtained if according to a further development of the invention the reinforcing preform receives a special construction. In particular the fitting edges are of an advantage, because they cause for example the pins to engage only the bottom of the reinforcing preform while at the same time effecting a lateral fixing of the same. The arrangement of more than two fitting edges (i.e. shoulders) has the advantage that the same reinforcing preforms can be used for different profile forms, because a lateral fixing with the aid of the fitting edges makes it possible for different preform to be fixed in position by fixing pins arranged at such points on the form which do not form later visible sides of the profile.